Recoll is a full text search application. Full text search applications let you find your data by content rather than by external attributes (like a file name). More specifically, they will let you specify words (terms) that should or should not appear in the text you are looking for, and return a list of matching documents, ordered so that the most relevant documents will appear first.

You do not need to remember in what file or email message you stored a given piece of information. You just ask for related terms, and Recoll will return a list of documents where those terms are prominent, in a similar way to Internet search engines.

Recoll uses the Xapian information retrieval library as its storage and retrieval engine. Xapian is a very mature package using a sophisticated probabilistic ranking model. Recoll provides the mechanisms and interface to get data into and out of the system.

Recoll Installation:
Recoll is available in Ubuntu repositories , you can install it in Ubuntu from Ubuntu Software Center or by running the following commands in the terminal.

sudo apt-get install recoll

Using Recoll:
* Start the recoll program fromt the Ubuntu Dash or from (Application > Accessories > Recoll)
* Possibly choose a search mode: Any term, All terms, File name or Query language.
* Enter search term(s) in the text field at the top of the window.
* Click the Search button or hit the Enter key to start the search.

The initial default search mode is Query language. Without special directives, this will look for documents containing all of the search terms (the ones with more terms will get better scores), just like the All terms mode which will ignore such directives. Any term will search for documents where at least one of the terms appear.